Maybe I can help, but we'll need to discover the appropriate file names.
I installed FSG mesh for all of North America many years ago on a different computer. When that rig failed, it was possible to recover my FS installations with the mesh, but the zip files they originally came in, and any instructions or identifying information were lost.
I just looked in my Mesh folder I see that some of the the file names are somewhat suggestive but not really indicative in any detail. So I know that Idaho and the surrounding region are in there somewhere, but I have no idea how to identify which files or files cover it. I suspect there are more than one, since some files seem to cover various parts of the western states and others appear to cover certain national parks and other special places.
I'd be happy to share my files, but unless we can get some guidance about file names, I can't figure out which files you need.